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Articles by H. H Wang
Total Records ( 2 ) for H. H Wang
  C. C Lin , W. N Lin , W. J Wang , C. C Sun , W. H Tung , H. H Wang and C. M. Yang
  Aims

Vascular smooth muscle cells (VSMCs) that function as synthetic units play important roles in inflammatory diseases such as atherosclerosis and angiogenesis. As extracellular nucleotides such as ATP have been shown to act via activation of P2 purinoceptors implicated in various inflammatory diseases, we hypothesized that extracellular nucleotides contribute to vascular diseases via upregulated expression of inflammatory proteins, such as cyclooxygenase (COX-2) and cytosolic phospholipase A2 (cPLA2) in VSMCs.

Methods and results

Western blotting, promoter assay, RT–PCR, and PGE2 immunoassay revealed that ATPS induced expression of COX-2 and prostaglandin (PGE2) synthesis through the activation of p42/p44 MAPK (mitogen-activated protein kinase), p38 MAPK, and nuclear factor-B (NF-B). These responses were attenuated by inhibitors of MAPK/ERK kinase (MEK1/2; U0126), p38 MAPK (SB202190), and NF-B (helenalin), or by tranfection with dominant negative mutants of p42, p38, IB kinase (IKK), and IKKβ. Furthermore, the ATPS-stimulated translocation of NF-B into the nucleus and degradation of IB was blocked by U0126 and helenalin. In addition, the ATPS-stimulated cPLA2 expression was inhibited by U0126, SB202190, helenalin, celecoxib (a selective COX-2 inhibitor), and PGE2 receptor antagonists (AH6809, GW627368X, and SC-19220). However, the inhibitory effect of celecoxib on cPLA2 expression was reversed by addition of exogenous PGE2.

Conclusion

Our results suggest that in VSMCs, activation of p42/p44 MAPK, p38 MAPK, and NF-B is essential for ATPS-induced COX-2 expression and PGE2 synthesis. Newly synthesized PGE2 was observed to act as an autocrine signal contributing to cPLA2 expression, which may be implicated in inflammatory responses. Collectively, our findings provide insights into the correlation between COX-2 and cPLA2 expression in ATPS-stimulated VSMCs with similar molecular mechanisms and functional coupling to amplify the occurrence of vessel disease-related vascular inflammation.

  M Watanabe , M Yumoto , H Tanaka , H. H Wang , T Katayama , S Yoshiyama , J Black , S. E Thatcher and K. Kohama
 

To explore the precise mechanisms of the inhibitory effects of blebbistatin, a potent inhibitor of myosin II, on smooth muscle contraction, we studied the blebbistatin effects on the mechanical properties and the structure of contractile filaments of skinned (cell membrane permeabilized) preparations from guinea pig taenia cecum. Blebbistatin at 10 µM or higher suppressed Ca2+-induced tension development at any given Ca2+ concentration but had little effects on the Ca2+-induced myosin light chain phosphorylation. Blebbistatin also suppressed the 10 and 2.75 mM Mg2+-induced, "myosin light chain phosphorylation-independent" tension development at more than 10 µM. Furthermore, blebbistatin induced conformational change of smooth muscle myosin (SMM) and disrupted arrangement of SMM and thin filaments, resulting in inhibition of actin-SMM interaction irrespective of activation with Ca2+. In addition, blebbistatin partially inhibited Mg2+-ATPase activity of native actomyosin from guinea pig taenia cecum at around 10 µM. These results suggested that blebbistatin suppressed skinned smooth muscle contraction through disruption of structure of SMM by the agent.

 
 
 
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